False-twist spindle



Feb. 1, 1966 H. CROUZET 3,232,037

FALSE-TWIST SPINDLE Filed April 24, 1964 2 Sheets-Sheet 1 INVENTOR.HENRI CROUZET awn/M 4, $1 g his A TTOR/VEYS Feb. 1, 1966 H. CROUZET3,232,037

FALSE-TWIST SPINDLE Filed April 24, 1964 2 Sheets-Sheet 2 INVENTOR.HENRI CROUZET his ATTORNEYS United States Patent 3,232,037 FALSE-TWISTSPINDLE Henri Crouzet, Roanne, France, assignor to Ateliers Roannais deConstructions Textiles, Roanne, France, a society of France Filed Apr.24, 1964, Ser. No. 362,519 Claims priority, application France, Apr. 26,1963,

932,803 14 Claims. (Cl. 5777.45)

As is well known in the art, stretch fabrics are woven or knitted fromyarn having a permanent curl. A falsetwist apparatus is utilized toattain the desired curl. The yarn is first twisted, and then byapplication of heat, for example, this twist may be permanently set inthe yarn. The yarn is then untwisted and wound on a bobbin ready forweaving or knitting. Because of the permanent set in the untwisted yarn,which causes it to tend to return to its twisted condition, the desiredstretch property is obtained in the woven fabric. The false twist isapplied to the yarn by a rotating spindle or tube through which the yarnpasses, suitable elements being provided within the tube for engagingthe yarn. It will be apparent that .the rate at which the yarn may befed through the false-twist tube is limited by the rotational speedwhich can be imparted to this tube.

False-twist apparatus has been used in the past which supported thefalse-twist tube magnetically, however there are disadvantages in theprior art devices. Patent No. 687,428, issued November 26, 1901,discloses apparatus for rotating a shaft, spindle or the like, whereinthe shaft (of magnetizable material) is held against two bearing disksby an electromagnet located between .the bearing disks. Thus the holdingforce is applied to the shaft at its central portion resulting ininstability because of the wobbling of the shaft permitted about an axisperpendicular to the shafts longitudinal axis. Another disadvantage ofthe apparatus is the complicated mounting of the elements necessary whenthe electromagnet is disposed between the bearing disks. French PatentNo. 1,239,013, issued July 11, 1960, discloses a falsetwist apparatuswherein the spindle is held against two pulleys so disposed that thedisks of one pulley partially overlap those of the other. Once again. afixed magnet is located between the disks of bothpulleys. It isimmediately apparent that thisapparatus is quite complicated andcumbersome. Furthermore, there is considerable contact friction betweenthe spindle and the pulleys, there being four disks in contact with thespindle. Moreover, a loss of driving power results from an arrangementin which two pulleys must be driven. Patent No. 3,059,408, issuedOctober 23, 1962, discloses a magnetically supported false-twist tube,wherein a driving belt or similar element is disposed between and incontact with fixed magnet pole tips and the floating falsetwist tube.Here a foreign element (the driving belt) is introduced into themagnetic circuit, i.e., is driven through the flux path between themagnet and the false-twist tube. Furthermore, there is considerablefriction and consequent heating developed between the driving belt andthe stationary magnet. Also, the belt must be driven at very high speed,since the speed step-up afforded by a pulley is not available.

Accordingly it is an object of this invention to provide a new andimproved false-twist apparatus which effectively overcomes theabove-mentioned disadvantages of the prior art.

Another object of the invention is to provide an apparatus for rotatinga shaft or the like at. very high speeds, for example 300,000 to 600,000revolutions per minute or even faster.

A further object of the invention is to provide a falsetwist apparatusof simple and compact design which is capable of rotating a yarn atconsiderably higher speeds than the conventional devices now in use.

These and other objects of the invention are attained by providing aspindle or false-twist tube of magnetizable material which floats freeof any bearings. The spindle is held against a drive element, formed oftwo parallel disks coaxially mounted on a rotatable shaft, by means of.a magnet, the poles of which are disposed externally of the disks ofthe drive element. The spindle is thus disposed against the peripheralsurfaces of the disks in parallel relationship with the rotatable shaft.Alternatively, a magnet arrangement may be employed having one polepiece disposed between the disks andtwo other pole pieces (of oppositepolarity from the first) disposed externally of the disks.

Further objects and advantages of this invention will be apparent from areading of the following detailed description in conjunction with theaccompanying drawings showing preferred embodiments, in which:

FIG. 1 is an elevational view, partly in section, of a typicalfalse-twist apparatus in accordance with the invention;

FIG. 2 is a top plan view of the apparatus of FIG. 1;

FIG. 3 is an elevational view, partly in section, of another embodimentof a false-twist apparatus according to the invention;

FIG. 4 is an elevational view of still another embodiment of afalse-twist apparatus according to the invention;

FIG. 5 is an elevational view of still another embodiment of afalse-twist apparatus according to the invention;

FIG. 6 is an elevational view looking from the left in FIG. 5;

FIG. 7 is a top plan view of the apparatus of FIG. 5; and

FIG. 8 is an elevational view looking from the right in FIG. 5.

In the typical embodiment of the invention shown in FIGS. 1 and 2, afalse-twist apparatus 10 comprises a shaft 11, preferably ofnon-magnetizable and electrically non-conductive material, supported forrotational movement in a base structure 12 by means of the bearings 13.The shaft 11 carries a pulley 14, preferably of non-magnetiza-ble andelectrically non-conductive material, having two disks 15 which areparallel to each other and coaxial with the shaft 11. The two disks 15may each be provided with a sleeve (not shown) of material with a highco-efficient of friction, such as natural or synthetic rubber. A belt 16is in driving engagement with the pulley 14 and, in order to support aspindle presently to be described, a stationary magnet 17, having polepieces 18 and 19, is disposed so that the pole pieces 18 and 19 arepositioned externally of the disks 15. The pole piece 19 is providedwith a bore 20 of sufficient diameter to permit the shaft 11 to rotatefreely without making contact with the pole piece 19. The pole pieces 18and 19 taper near their extremities to form relatively narrow protrudingportions or tips 21, as best illustrated in FIG. 2.

A false-twist tube or spindle 22 comprises a tubular body 23, preferablyof magnetizable material, having a bore 24 extending through the lengthof the body 23. The

bore 24 is of suitable diameter to permit passage therethrough of theyarn 25 (shown in phantom) to be twisted. Within the false-twist tube 22is an element 26 (for example, as disclosed in British Patent No.881,788 published November 8, 1961), preferably of non-magnetizable andelectrically non-conductive material, for engaging the yarn 25. Twocollars 27 of magnetizable material are formed upon the tube 22, beingspaced to agree with the spacing of the magnetic pole pieces 18and 19.

In operation, stationary magnet 17 exerts holding forces upon thecollars 27 of the false-twist tube 22. These forces hold the tube 22firmly against the disks 15 of'the pulley 14 and since the holdingforces are applied near the extremities of the tube, the stability ofthe tube is assured since undesirable wobbling is avoided. Directing theapplication of force by concentrating the magnetic flux through thesmall protruding portions or tips 21 contributes to the stability. Whenthe pulley is rotated by the belt 16, the rotation of the pulley istransmitted to the false-twist tube due to is contact with theperipheral surfaces of the disks. It thus becomes possible to rotate thefalse-twist tube at speeds of 300,000 to 600,000 revolutions per minuteand higher. Since the tube is floating free of any bearings and there isonly rolling friction along one lineof contact with the disks, the heatgenerated in the tube is minimized. Furthermore, if the pulley' is ofnon-magnetizable and electrically non-conductive material, heating ofthe pulley due to eddy currents is avoided. 7

FIG. 3 illustrates another embodiment of the invention. Here the pulley14, having a shaft 14A and disks 15, is carried by the shaft 11, whichis supported for rotational movement in the base structure 12 by meansof the bearings 13, as in the first embodiment. The pulley 14 is drivenby the belt 16 which is in driving engagement with a collar 30 securedto the shaft 11 by any conventional means. A stationary magnet 31comprises the three pole pieces 32, 33 and 34, the two end pole pieces32 and 34 being of one polarity, while the center pole piece 33 is ofthe opposite polarity. If desired, the magnet 31 may comprise twocomponent magnets placed back-to-back as illustrated in FIG. 3, onecomponent magnet having pole pieces 32 and 33A and the other componentmagnet having pole pieces 33B and 34. The pole piece 34'has a bore 35 ofsufficient diameter to permit the shaft 11 to rotate' freely withoutmaking contact with the pole piece 34. Similarly, there is a bore 36 inthe pole piece 33 of sufficient diameter to permit the pulley shaft 14Ato rotate freely therein. The pole pieces 32 and 34 at their extremitiestaper to form the same relatively small protruding portions or tips 21which are best illustrated in FIG. 2. The central pole piece 33 isslightly shorter in length than the end pole pieces 32 and 34. Theextremity of the pole piece 33 has a central concave portion 37 and twopole tips 38. I

A'false-twist tube or spindle 39 comprises a tubular body 40 ofmagnetizable material having a bore 41 extending therethrough to permitpassage of'the yarn (not shown). The body 40 carries a collar 42 ofmagnetizable material, the collar having a central concave portion 43and protruding end rims 44. Here again there is provided a yarn-engagingelement 26.

The stationary magnet 31 exerts holding forces on the false-twist tubeat four points: viz. on the tubular body 40 opposite the protrudingportions 21 of the pole pieces 32 and 34, and on the end rims 44 of thecollar 42. The forces exerted by the pole pieces 32 and 34, beingapplied near the extremities of the false-twist tube, assure stabilityagainst wobbling-while the forces applied to the end rims 44 hold thefalse-twist tube against translational movement along its axis.Furthermore, the central portion of the collar 42 will be substantiallyfree of magnetic flux, the flux from the central pole piece 33 followingtwo paths through the end rims 44 and thereafter through the body 40 tothe adjacent one of the two end pole pieces 32 and 34. By so designingthe apparatus that the magnetic flux is essentially eliminated from thecentral portion of the collar 42, heating of the false-twist tube due toeddy currents is reduced.

FIG. 4 illustrates still another embodiment of the invention. Here themagnet 17 pulls the false-twist tube 22 against the pulley 14 as inFIGS. 1 and 2. Rather than driving the pulley 14 directly by the belt 16as in the first embodiment, the belt 16 is in driving engagement with acollar 30 affixed securely to the shaft 11 externally of the magnet 17,as in the second embodiment. This further simplifies the structurewithin the magnet 17, there being one less moving element'therein'.Furthermore, heating of the pulley and the false-twist tube by the beltis essentially eliminated. v I

FIGS. 5 through 8 illustrate still another embodiment of'the' invention.This is similar to the embodiment of FIG. 3, inthat a magnet arrangementis employed having one pole piece disposed between the disks 15 and twoother pole pieces (of opposite polarity from the first) disposedexternally of the disks, however the pole pieces are displaced or offsetfrom the axisof the pulley 14 and the shaft 11, so that no p'olepieceneed have a bore within which the pulley or shaft may rotate.Furthermore, the tips of the pole pieces are formed differently fromthose in the prior embodiments.

The shaft ll'is supported for rotational movement in abase'pl'ate 45 bymeans of suitable bearings (not shown). The shaft 11'is driven by thebelt 16 which is in driving engagement with the collar 30, as in theembodiments illustrated in FIGS. 3 and 4. The shaft carries the pulley14, preferably of non-magnetizable and electrically non-conductivematerial, having the two disks 15, as before. The two disks 15 may eachbe provided with a sleeve (not shown) of material with a' highcoeflicient of friction, su'ch as natural or synthetic rubber. Mountedon the base plate'45 is a'sta'tionary magnet 46 comprising the threepole pieces 47, 48'and 49, the two end pole pieces 47 and 49 beingof'one polarity while the center pole piece 48 is of the oppositepolarity. If desired, the magnet 46 may comprise'an E- shape'd base 50onwhich the pole pieces 47, 48 and 49'are mounted, as seen'in FIGS. 7 and8. With such a magnet arrangement, wherein the pole piecesare displacedor offset from the axis of the pulley' 14'and the shaft 11, asbestviewed in FIG. 7, no pole piece of'the'magnet 46 need' have a boreto permit the pulley or shaft to rotate freely therein, (such as thebores 20, 35 and 36 'in FIGS. 1 and 3). As may be best seen in FIG. 7,the ends 47, 48', and 49 of the pole pieces 47,48'and'49,'resp'ectively, extendradially from the axis of the pulley 14for reasons to be explained hereinafter.

A false-twist tube or spindle 51 comprises a tubular body 52 ofmagnetizable material having a bore 53 extending therethrough to permitpassage. of the yarn 25. The spindle is provided with a collar 54 withinwhich is disposed the yarn-engaging element 26, both preferably ofnon-magnetizable and electrically non-conductive material. Thestationary magnet 31 exerts holding forces on the spindle at threepoints, i.e., on the tubular body 52 opposite the pole piece ends 47',48 and 49. Inasmuch as these ends are disposed radially of the pulley14, the holding forces act along a radius of the pulley and thereforeperpendicularly of the peripheral surfaces 15a of the disks 15 at theline of contact between the spindle and the disks. There are air gapsbetween the spindle body 52 and the three pole piece ends 47, 48 and 49of approximately 0.3 mm. each.

The stability of the spindle against wobbling is assured by terminatingthe pole piece ends 47, 48 and 49 in a trapezoidal profile as viewed inFIG. 7 in order to concentrate the magnetic flux therethrough. The fluxis also concentrated in 'the vertical plane, i.e. as best viewed inFIGS. 6 and 8, by chamfering the surfaces 47a and 49a of "thepole pieceends 47 and 49', respectively, remote from each other. The length of themagnetizable portion of the spindle 51 is substantially that of thedistance between the outer edges 47b and 49b of the chamfered ends 47and 49, respectively, whereby the magnetic flux is concentrated so as tolimit longitudinal displacement of the spindle with respect to themagnet or pulley.

Although this invention has been described with reference to theforegoing specific embodiments, further modifications and variationswill readily occur to those skilled in the art. For example, the polepiece ends 47 and 49' could be formed with pointed tips inclined towardseach other. Therefore, the invention is not to be construed as limitedexcept as defined by the following claims.

I claim:

1. Apparatus for rotating a spindle, at least a portion of which is ofmagnetizable material comprising driving means having at least onecontinuous spindle-engaging surface and magnet means disposed externallyof the driving means for holding the spindle in driving engagement withthe spindle-engaging surface of the driving means.

2. Apparatus according to claim 1 wherein the driving means comprises arotatable element having a circular periphery adapted to engage thespindle.

3. Apparatus according to claim 1 wherein the driving means comprises aplurality of spaced disks adapted to engage the spindle.

4. Apparatus according to claim 1 wherein the driving means comprises aplurality of spaced disks adapted to engage the spindle and whereinthere is provided a spindle provided with enlargedmagnetizable portionsjuxtaposed with respect to the magnet means.

5. Apparatus according to claim 1 wherein the magnet means are formedwith relatively narrow pole tips spaced in close proximity to themagnetizable portions of the spindle.

6. A false-twist spindle and driving mechanism therefor comprising afalse-twist spindle formed of magnetizable material, spaced disks theperipheries of which are in driving engagement with the spindle, meansto rotate the disks, and magnet means spaced externally of the disks forholding the spindle in driving engagement with the peripheries of thespaced disks.

7. Apparatus in accordance with claim 6 wherein additional magnet meansis provided between the disks and the spindle is formed with an enlargedmagnetizable portion adjacent the last-named additional magnet means.

8. Apparatus in accordance with claim 7 wherein the additional magnetmeans is formed with a concave portion and spaced pole tips and theenlarged magnetizable portion of the spindle is formed with a concaveportion terminating in rims juxtaposed with respect to the lastnamedpole tips.

9. Apparatus according to claim 6 wherein the magnet means comprise twosets of adjacent magnets having their like poles spaced intermediatelyadjacent each other between the disks and the other of their polesspaced outside of the disks, all of said poles being inmagneticforce-applying relationship to the spindle, and the spindle isformed with an enlarged magnetizable portion adjacent the magnet polesbetween the disks.

10. Apparatus according to claim 9 wherein each of the magnet polesterminates in relatively narrow pole tips adjacent the spindle.

11. Apparatus according to claim 6 wherein additional magnet means isprovided between the disks and in magnetic-force-applying relation tothe spindle, all the magnet means being in offset spaced relation to thedisk rotating means.

12. Apparatus according to claim 6 wherein the magnet means comprisepole pieces chamfered at the end surfaces remote from each other.

13. Apparatus according to claim 6 wherein the magnet means comprisepole pieces formed with pointed tips inclined towards each other.

14. Apparatus according to claim 6 wherein the peripheries of the spaceddisks are formed with a material having a high coeflicient of friction.

References Cited by the Examiner UNITED STATES PATENTS 2,855,750 10/1958 Schrenk et a1. 57-77.45 X 3,059,408 l0/ 1962 Hippe et al57----77.45 3,142,953 8/1964 Gassner et a1. 57-77.45

FOREIGN PATENTS 862,319 3/ 1961 Great Britain. 908, 113 10/ 1962 GreatBritain.

MERVIN STEIN, Primary Examiner.

D. E. WATKINS, Assistant Examiner.

1. APPARATUS FOR ROTATING A SPINDLE, AT LEAST A PORTION OF WHICH IS OFMAGNETIC MATERIAL COMPRISING DRIVING MEANS HAVING AT LEAST ONECONTINUOUS SPINDLE-ENGAGING SURFACE AND MAGNET MEANS DISPOSED EXTERNALLYOF THE DRIVING MEANS FOR HOLDING THE SPINDLE IN DRIVING ENGAGEMENT WITHTHE SPINDLE-ENGAGING SURFACE OF THE DRIVING MEANS.